1. Field of the Invention
The present invention is generally related to communication devices and more particularly to an improved communication device operating within multiple communication systems.
2. Description of the Related Art
Communication devices operating within a single communication system are well known in the art. Such communication devices, for example, can include cellular telephones, wireless messaging devices, cordless telephones, two way radios, and the like. Recently, composite communication devices having the capability to operate within multiple communication systems are emerging in the marketplace. For example, one communication device can operate on both a cellular network and a two way radio network. Similarly, one communication device can operate on both a cordless telephone network and a two way radio network.
Cordless telephones typically are used in the home to allow the user to place and receive telephone calls at any point throughout the house. A cordless telephone system typically includes a portable cordless handset and a cordless base station connected to a telephone company phone system by telephone landlines. The cordless base station has an assigned landline telephone number that allows the user to place and receive calls using the cordless portable handset within a limited range of the cordless base station, such as in a home. However, due to their limited range, the cordless portable handset provides the user with relatively local radiotelephone communication. Further, a cordless telephone call is used generally for one to one communication via the landline communication system with limited capabilities for multi-device communication using conference calling options.
Radiotelephone communication outside the range of the cordless telephone system can be provided to a user via a two way radio system. A two way radio system typically includes a plurality of two way radio handsets communicating directly together on the same radio channel. When a user of a two way radio handset initiates a communication, the communication is transmitted to all the other two way radio handsets assigned to the same radio channel. In this manner, multiple handsets can communicate directly to each other.
Recently, some cordless telephones have been developed with handset to handset capability. These units do not provide group talk, but instead provide limited telephone inter-connect and one to one, full duplex radio capability.
Further, some new communication devices combine the mobility of a cordless telephone system with the immediacy of a two way radio system. Such combined devices provide accessibility to outside callers while staying in immediate contact with internal operations. In two-way radio mode, these devices provide instant communication with others utilizing two way radios on the same radio channel at the push of a button. In cordless telephone mode, these devices have similar functionality to standard landline telephones.